Ice melt 'due to warmer globe'

Page Tools

The loss of the great Antarctic ice shelf Larsen B is firming as a milestone sign that human activity is warming the world.

Scientists disclosed yesterday that the shelf had existed for at least 10,000 years before disintegrating. Its rate of melting had accelerated in recent decades.

It is almost certainly a response to human-induced global warming, said Canadian geographer Robert Gilbert.

Larsen B was the subject of a spectacular fictionalised opening sequence in the climate change movie, The Day After Tomorrow. The break-up of the 3250-square-kilometre floating shelf has undergone intense scientific scrutiny since it shattered in just 35 days in early 2002.

As one consequence, onshore glaciers held back by the shelf have been unleashed. They are surging down to the sea up to eight times faster than before, said Ted Scambos, from the US National Snow and Ice Data Centre.

Professor Eugene Domack, from Hamilton College in the US, concluded in the journal Nature that Larsen B's loss was unprecedented since the last ice age, or in the current geological epoch, known as the Holocene.

"Our observation, that the modern collapse of (Larsen B) is a unique event within the Holocene, supports the hypothesis that the current warming trend in the north-western Weddell Sea has exceeded past warm episodes in both its magnitude and duration," he said.

Over the past 50 years local temperatures have risen around 2 degrees. In recent years the peninsula has lost ice shelves totalling more than 12,500 square kilometres.

A British Antarctic Survey study found that 87 per cent of all 244 glaciers draining inland ice to peninsula shelves had retreated.

The loss of a floating ice shelf does not raise sea level. But onshore glacier loss is different.

"So that is having, and will have, an effect on sea levels," said Dr Gilbert, from Queen's University, Canada.